This invention relates to an overhead conveyance device and an overhead conveyance vehicle that travels along an overhead track to convey a conveying object (a carrier) between processing units disposed in a cleanroom and the like, after putting the carrier in its suspended state.
For example, a conveyance system configured in a cleanroom for wafers used for manufacturing semiconductor devices uses an overhead conveyance vehicle that travels along an overhead track to convey a wafer-containing carrier between semiconductor processing units or between a semiconductor processing unit and a stocker and handler. The overhead conveyance vehicle comprises a carriage part that travels along a track, a hand suspending part provided in the carriage part, and a hand suspended from the hand suspending part in such a manner as to freely move up and down. The overhead conveyance vehicle is so structured that the hand grasps a carrier put on a load port of the processing unit; the hand suspending part raises the hand; and the carriage part travels along the track.
In this conveyance system, a rotary branching part (turning table type) is located in the track at a proper place thereof, in order to increase a conveyance rate per unit of time or shorten the conveyance time. In the branching part, the conveyance vehicle grasping the carrier is made to turn around 90 degrees.
Incidentally, many wafer containing carriers have a configuration in which protrusion of the carrier from the center varies as the carrier turns around. These types of carriers have a configuration of an oval cut in half, not a circular configuration, when viewed from the top. Due to this, when the rotary branching part is located over the processing unit, the turntable carrier must be kept at a sufficient distance from the processing unit, in order to prevent interference with the processing unit.
In the conveyance system above, the tracks for conveying the carrier between these units are placed, after a plurality of processing units are located in the cleanroom. If the tracks are placed with reference to the maximum protrusion of the carrier, that would limit the placing of the tracks, complicate the conveyance route and require an increased size of the entire building. Also, that could exert an influence upon the number and relative relationships of opposite processing units arranged in parallel, depending on the placing of the tracks.
It is an object of the invention to provide an overhead conveyance device and an overhead conveyance vehicle that can convey a conveying object, while keeping it at a minimum distance from a processing unit when the overhead conveyance vehicle conveying the conveying object changes direction.
According to the first invention, a rotary branching part to allow an overhead conveyance vehicle to change direction is located in an overhead track. The overhead conveyance vehicle has a hand suspending part rotatable relative to the carriage part, which travels along the track, a hand part suspended from the hand suspending part in such a manner as to be movable up and down, and driving means for rotating the hand suspending part relative to the carriage part in the opposite direction when the carriage part travels into the branching part and turns.
According to the second invention, there are provided control units for recognizing an extent of rotation of the branching part and driving the driving means, in addition to the features of the first invention. The extent of rotation of the branching part includes the one using optical communications to receive an rotation angle of the branching part, the one using an angle detecting device, such as a gyro, built in the hand suspending part, and a distance sensor for detecting a distance between the hand suspending part and the processing unit.
According to the third invention, a rotary branching part to allow the carriage part to change direction is located in the overhead track. Further, there are provided a first fixing means that permits the carriage part to turn relative to the hand suspending part but prevents the hand suspending part from turning when the carriage part is turned by the branching part; and a second fixing means that prevents the hand suspending part from turning relative to the carriage part during the usual traveling of the carriage part.
According to the fourth invention, in addition to the features of the third invention, there are provided the first fixing means located on the track side and a stopper located in such a manner as to be movable back and forth with respect to the hand suspending part. A linear actuator located in a support of the branching part in such a relation as to be movable back and forth with respect to a corner or a projection of the hand suspending part is cited as an example of the stopper.
According to the fifth invention, there are provided a carriage part that travels along an overhead track, a hand suspending part mounted on the carriage part in rotatable relation relative thereto, a hand part suspended from the hand suspending part in such a manner as to be movable up and down, and rotation control means for controlling turning of the hand suspending part relative to the carriage part.
According to the first and second invention, when the carriage part of the overhead conveyance vehicle travels into the rotary branching part and starts to turn, the extent of the turning is recognized and the hand suspending part can be turned relative to the carriage part in the opposite direction to the extent corresponding to the extent of the turning. This can permit only the carriage part to change in direction, without changing the direction of the conveying object grasped by the hand part. This enables the overhead conveyance vehicle to branch off, keeping the conveying object at a minimum distance from the processing unit. The processing units are not subject to the constraints resulting from the turning of the conveying object, such as reduction of their heights or widening of an interval between adjoining processing units arranged in parallel. As the processing units are commonly crowded into a limited place in a cleanroom, liberalization from those constraints can produce the advantageous effects that the number of processing units to be located can be increased and that the conveyance route is not required to be complicated. Also, since the overhead conveyance vehicle controls the turning of the hand suspending part, the branching part is not required to be complicated in structure.
According to the third and fourth invention, when the carriage part travels into the rotary branching part and starts to turn, the second fixing means is switched to OFF and the first fixing means is switched to ON to keep the hand suspending part unchanged in direction. This can permit only the carriage part to change in direction, without changing the direction of the conveying object grasped by the hand part. This enables the overhead conveyance vehicle to branch off, keeping minimal the distance between the conveying object and the processing unit. Also, the processing units are not subject to the constraints resulting from the turning of the conveying object, such as reduction of their heights or widening of an interval between adjoining processing units arranged in parallel. As the processing units are commonly crowded into a limited place in a cleanroom, liberalization from those constraints can produce the advantageous effects that the number of processing units to be located can be increased and that the conveyance route is not required to be complicated. Also, although the branching part is required to have the first fixing means, since the overhead conveyance vehicle is simply required to have the second fixing means, the overhead conveyance vehicle is not required to be complicated in structure.
According to the fifth invention, since the hand suspending part is turned under control of the rotation controlling means, the conveying object grasped by the hand part can be freely changed in direction on the conveyance way. The conveying object can be prevented from interfering with the processing unit in the conveyance by changing the direction of the conveying object.